Self-ejecting breech



United States Patent 3,030,864 SELF-EJECTING BREECH C Walton Musser, Beverly, Mass., assignor to the United States of America as represented by the Secretary of the Army The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to recoilless guns, and more particularly to the provision of an improved gun which is light in weight and is so constructed as to avoid the expenditure of time heretofore required for unloading a spent cartridge case.

An important item in reducing the weight of this improved gun is a breech mechanism involving only a groove on the inner surface of the gun barrel and a split ring which protrudes from this groove for locking the cartridge case to the barrel and is forced out into the groove for releasing the cartridge, this action being automatically produced by recocking of the gun. The time heretofore required for unloading a spent cartridge case is saved by the provision of a firing pin hammer which is operable (1) to recock itself in response to a blast of gas produced by firing of the gun, (2) to release the spent cartridge case during this recocking operation, and (3) to reset the firing mechanism in a safe condition.

The invention will be better understood from the following description considered in connection with'the accompanying drawings and its scope is'indicated by the appended claims.

Referring to the drawings:

'FIG. 1 is a sectional View illustrating various features of the gun and the cartridge which it is adapted to fire,

FIG. 2 shows the gun as viewed from the breech end,

FIG. 3 is an underside view of the breech end of the FIG. 4 illustrates the relation between the sear and a safety actuator,

FIG. 5 illustrates the safety in the ready to fire position,

FIG. 5A illustrates a means for locking the firing mechanism against accidental operation, and

FIGS. 6, 7 and 8 are difierent views of the means which are operated in response to movement of the hammer and function to expand the split ring for releasing the case of the fired cartridge.

FIG. 1 shows a gun having a barrel 10 which is encircled by a chamber 11. At its forward end, this chamber is locked to the barrel by a nut 12, and, immediately to the rear of this nut, the barrel has a plurality of apertures 13.

A slot 14 at the breech end of the barrel 10 is adapted to receive a split ring 15 arranged to cooperate with the case 16 of a cartridge which includes a primer 17 for igniting a propellant enclosed in a combustible case 18 extending from a projectile 19 to the case 16. Around the primer are a plurality of vents 20 through which a blast of gas is ejected when the gun is fired.

The barrel 10 and the chamber 11 are cut away as indicated in FIG. 1 to accommodate the firing mechanism of the gun. A separator 21 fits between the barrel and chamber. Within the separator are housed a sear 22, a safety 23 and a safety actuator 24. The separator 21 holds the barrel and chamber in the correct relationship by means of screws extending through these parts.

A hammer 25, having a firing pin 26, a shaft 27 and a spring 28, fits into slots in the separator 21. As indicated by FIGS. 1, 4, 5 and 6, the hub of the hammer has a groove 37 on its outer periphery. It also has a cam-shaped surface 36 at one of its sides as shown in FIGS. 4, 5 and 6. As shown more clearly in FIG. 4, one end of the sear 22 is held in the groove 37 by a spring 38 and one end of the safety actuator 24 rides against the cam-shaped surface 36. The respective lengths of the groove 37 and cam-shaped surface 36 circumferentially about the hub of the hammer 25 are indicated by FIG. 6, the actual location of the groove 37 being shown on FIG. 1. In a counterclockwise direction around the hub of the hammer andjust ahead of the groove 37, the hub is recessed to form a wedge-shaped projection 32. As hereinafter explained, this projection rides between a pair of lugs 33 and 34 on the split ring 15 for releasing the cartridge case 16 after it has been fired.

The breech end of a firing cable assembly, including an adjuster 29, is held in place by a cover 30 (FIGS. 1 and 3).

The various parts of the gun are shown as in their Ready-to fire position. With the hammer 25 in its illustrated position, firing of the gun is eifected by pulling a cable 31. The hammer spring 28 is of the clock type and is so wound that when the sear 22 is released, the hammer is driven clockwise until the firing pin 26 strikes the primer 17. This fires the primer and ignites the propellant enclosed in the combustible casing 18.

As the propellant powder begins to burn, pressure is built up in the case 18 and gas escapes through the vents 20, through the apertures 13 and through the venturi at the breech end of the chamber. The gas ejected through the vents 20 impinge on the race of the hammer 25 and drive it in a counterclockwise direction. The hammer returns to the position shown in FIG. 1 and its inertia keeps it moving in a counterclockwise direction for another degrees.

During the first part of this 90 degrees, the hammer 21 earns the split ring 15 open as indicated by FIG. 6, which is a development of the outside of the hammer in a counterclockwise direction. This opening of the split ring is efiected by a pointed part 32 arranged to separate the ends 33 and 34 (see FIG. 8) as the hammer rotates in a'counterclockwise direction. This forces the spring 15 into the groove 14 thereby releasing the cartridge case 16 and allowing it to be blown out by the residual gas in the barrel 10. The action of this mechanism is so regulated that the projectile leaves the muzzle somewhat before the case is released. is efiected by suitable proportioning of the weight of the hammer, the pressure of the spring and the size of the vents around the primer.

During the last part of the 90 degree movement of the hammer in a counterclockwise direction, a cam on the side of the hammer drives the safety actuator 24 which turns the safety 23 counterclockwise. This locks the sear 22 in a position where its end extends into the groove 37 and returns the firing cable 31 to the position indicated in FIG. 5 where the safety 23 is under aprojection 35 on the cable adjusting 29 so that the cable cannot be actuated until the safety 23 is returned manually from the safe to the fire position as shown in FIG. 5. Meanwhile, the spring 28 returns the hammer to the positions indicated in FIG. 1.

The projectile shown in FIG. 1 is of the fin-stabilized type. It is held to the head of the cartridge case by means of a shot-start device which prevents movement of the projectile until a certain chamber pressure is reached. It has a rotating band which gives it a slow spin as it passes along the shallow groove rifling of the barrel.

I claim:

1. The combination of a gun having a barrel with an interior circumferential groove near its breech end, a cartridge having a case with an exterior groove near its breech end and having in its breech end a primer with an opening into the interior of said shell, a split ring extend- 3 ing at one side into one of said grooves and at the other side into the other of said grooves, said ring having lugs at its opposite ends, a spring biased sear, a safety operable to look said sear against movement, an actuator for said safety, resilient means, and a trigger pivoted to said barrel and having an inertia such that it is driven by said resilient means from its cocked position into contact with said primer and has imparted to it by the gas discharged through said opening upon the firing of said cartridge a motion extended beyond said socked position, said trigger having a hub upon which are a wedge-shaped projection adapted to engage said lugs and release said case at an early point in said extended motion, a groove adapted to motion in the cocked position of said trigger, and a earnshaped surface engaging said actuator for operating said safety to lock said sear against movement.

2. A combination according to claim 1 wherein said extended motion comprises a travel of substantially 90 beyond said cocked position.

3. A combination according to claim 1 wherein a firing cable is attached to said sear and wherein said safety is operable to lock said cable against movement.

References Cited in the file of this patent UNITED STATES PATENTS 2,920,533 Musser Jan. 12, 1960 FOREIGN PATENTS 146,656 Australia Aug. 31, 1950 1,195,226 France Mar. 19, 1959 

